Method of making heat-exchanger tubes



Dec. 30, 1930. w. LONSDALE 57 METHOD OF MAKING HEAT EXCHANGER TUBES Filed Feb. 27. 1929 'INVENTOR Patented Dec. 30, 1930 UNITED-STATES PATENT OFFICE WILLIAM LONSDALE, OF ROSELLE PARK, NEW JERSEY, ASSIGNOR TO FOSTER WHEELER CORPORATION, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK METHOD OF MAKIITG HEAT-EXCHANGEB TUBES Application filed February 27, 1929. Serial No. 343,221.

My present invention relates to a method of making tubes for heat exchange apparatus and more particularly to a method by which a seamless tube is so constructed as to be provided with one or more fins or lateral projections which may extend longitudinally of the tube, or may be disposed in a spiral relationship thereto. The form of tube to which my invention relates is adapted for use in various types of heat exchange apparatus, for example, it may be advantageous for use in boilers, condensers, feed water heaters, super heaters, economizers, and various types of heat exchangers utilized in refining oil. The purpose of so constructing the tube is to increase the heat transfer surface thereof.

I am aware that heretofore in various or a series of such sleeves, spaced relatively close to each other and shrunk on the tube so as to provide an extended area for increasing the heating surface. I am also aware that heretofore in tubes employed in condensers and other forms of heat exchange apparatus the tubes have been provided with laterally extending fins or webs. In all instances of this kind, however, so far as I am aware, each tube has been constructed in parts and the parts welded together, or otherwise connected to one another. Inthe use of tubes of this type in heat exchange apparatus, whether the tubes are provided with flanged collars and shrunk thereon, or whether the tubes are made in parts and welded together, there is the ever present likelihood of the parts working loose and thereby impairing the heat transfer efficiency of the apparatus in which the are employed.

he object of my invention is the provision of a tube so constructed that the same includes no parts to work or otherwise become loose and to thereby furnish a tube of relatively greater strength and one in the use of which the efficiency of the apparatus cannot well .be affected by, or through any fault of the tube until the tube itself has been worn out. in carrying out the invention I produce seamless ribbed tube as will be hereinafter more particularly described.

In the drawing Figure lis a perspective view illustrating a heat exchanger tube made in accordance with this invention.

Fig. 2 is a section on line 22, Fig. 1,

Figs. 3 to 8 inclusive are illustrative of the manner of forming the tube and in these illustrations Fig. 3 is a longitudinal elevation of a tube,

Fig. 4 is a section on line 44, Fig. 3,

Fig. 5 is an elevation illustrating the form the tube assumes after the first operations thereon,

Fig.6'is a section on line 66, Fig. 5,

. Fig. 7 is an elevation of a tube after the fins have been formed therein and the cross section of the body of which is preciselythe sameasshown in Fig. 2,

Fig. 8 is an elevation showing a tube with spirally disposed fins thereon.

The heat exchanger tube formed in accordance with my present inventionpreferably .consi'sts of a cylindrical body portion 10 made of any suitable metal and in any necessary length. The tube is formed as hereinafter described to include oppositely disposed f ns or flanges 11 and 12 which may be made to extend longitudinally of the body of the tube and to be integraltherewith so that the tube is seamless. Also as hereinafter. described the fins or flanges may be made to extend spirally of the body of the tube without departing from the invention. As illustrated in Figs. 1 and 2 the parts of the fin 11 r are indicated at 13 and 14, and the parts of the fin 12 at 15 and 16, and these parts respectively are preferably made to contact with each other along their inner faces, as indicated at 17 and 18. although, of course, in some instances it may be necessary or de' sirable to leave an appreciable space between the inner faces of the parts of the tube form .ing either or both, or all, of the fins or the flanges associated therewith, it being under stood that the tube as shown in Figs. 1 and 2 having oppositely disposed fins is merely illustrative of the type of tube made in accordance with the invention and that the number of these fins may be more or less as the use of the invention requires, it furthermore being understood that the fins may be made to extend any predetermined portion of the length of the tube and that also the cylindrical end portions of the tube may be of any required length.

in forming this heat exchanger tube 1 take a tubular body 19 appreciably larger in cross section than the tubular body of the finished tube. The tubular body in its original form is illustrated in lFigs. 3 and l. The tubular body first has either one or both end portions thereof swaged so as to be of ma terially reduced cross section. F or example, the left hand end of the tubular body, as indicated in Fig. 5, is swaged to include a portion 21 which may be substantially cylindrical and an extreme portion 22 which is preferably conical. ltn like manner the opposite end of the tubular body 19 may be swaged to have a cylindrical portion 21 of reduced cross section and a conical extremity 22. The respective extremities of the tube are then successively engaged by a drawbench tongs and drawn through a die so that first the portion 21 and then the portion 21' are drawn to an exterior diameter the same as that desired in the finished product. This is the end portion 10, as indicated in Fig. 1. Next the tube thus formed is drawn through a die having belled entrance slots whereby the originally larger portion of the tube intermediate of the thus reduced ends thereof is formed to provide the ribs irrespective of the number thereof.

In thus reducing the intermediate portion of the tube the body thereof, as indicated at 23, is of substantially the same exterior and interior diameter as the end portions 21 and 21 thereof, while the ribs 24: and 25 may be made, as now will be readily understood, to extend any desired proportion of the length ofthe finished tube. \Vith the tube thus formed the rough taper extremities thereof are then sawed or otherwise cut off, leaving the substantially parallel cylindrical ends which are uniform in diameter with the intermediateparts of the body of the tube in which the fins are formed, as shown in Fig. 7.

As illustrated in Fig. 8 the fins 27 extending from the cylindrical body 28 of the tube may be so constructed as to form a helix by twisting the tube, or if necessary in any instances where the pitch of the helix is extreme or acute, the spiral fin may be formed by rotating the die at the same time the main or body portion of the tube is drawn therethrough to form the fins.

Due to the fins extending from the body of the tube the heat exchange surface thereof is materially increased and because of the fact that the fins are made integral with the body of the tube there is substantially no liability of their being separated therefrom, resulting in a greater elliciency of the apparatus in which the tubes are employed and also resulting in a much longer life of each tube. it is to be understood as coming within the structure as contemplated by the invention to make a tube having any desired number of fins and place them longitudinally of, or spirally with, or in any other association with the body of the tube, and furthermore that irrespective of the configuration of the tin or fins these parts may, if necessary or desirable, be continued to either or both ends of the tube with which they may be associated.

1 claim as my invention:

1. The method of making a seamless heat exchanger tube consisting in first reducing an end portion of an oversized tubular body to the desired transverse section of the finished tube, and then forming an integral fin in the over-sized tubular body and in doing so reducing its transverse section to that of the previously reduced end portion thereof.

2. The method of making a seamless heat exhanger tube consisting in reducing an end portion of an oversized tubular body to a cylindrical part with a transverse section of that of the finished tube and a conical c2;- tremity, and then forming an integral fin in the oversized tubular body and in so doing reducing its transverse section to that of the cylindrical part of the reduced end portion thereof. 1

3. The method of making a seamless heat exchanger tube consisting in swaging an end portion of an oversized tubular body to substantially the desired transverse section of the finished tube, then drawing the swaged end portion of the oversized body through a die to the desired transverse section of the finished tube, and then forming an integral fin in the oversized tubular body and in so doing reducing its transverse cross section to that of the drawn end portion thereof.

4. The method of making a seamless heat exchanger tube consisting in swaging an end portion of an oversized tubular body to cause the said end portion to include a cylindrical part of substantially the desired transverse section of the finished tube and an extremity of conical configuration, then drawing the cylindrical part of the reduced end through a die to cause the same to-be of the same transverse section as the finished tube, and then formingan integralfin in'the oversized tubular body and in so doing reducing its verse section as that of the finished tube, and

an extremity of conical configuration, then drawing the said reduced end of the tube through a die to further reduce the same to the transverse section of the finished tube, and then drawing the oversized tubular body through a die to form an integral fin thereon and in so doing to reduce the transverse section of the oversized tubular body to that of the previously reduced end portion thereof.

.6. The method of making a seamless heat exchanger tube consisting in swaging an end 7 portion of an oversized tubular body to have a cylindrical part of substantially the same cross section of the finished tube and a coni cal part at the extremity thereof, then drawing the cylindrical reduced end part through a die to the transverse sect-ion of the finished tube, then drawing the said oversized tubular body through a die having a "belled entrance slot therein to form an integral fin and reduce the transverse section thereof to that of the cylindrical part of the previously reduced end portion, and then cutting ofi the conical extremity at the end of the tube.

7 The method of making a seamless heat exchanger tube consisting in reducing por-- tions at both. ends of an over-sized tubular body to the transverse section of thefinished tube, and then forming an integral fin in the oversized tubular body and in so doing re ducing the transverse section thereof to that 0% the previously reduced end portions there- 0 8. The method of making a seamless heat exchanger tube consisting in reducing a portion at both ends of an oversized tubular body -so that both end portions comprise a cylindrical part having a transverse section of the finished tube and'a conical part at the extremity thereof, and then forming an integral fin in the said oversized tubular'cbody and at the same time reducing the transverse Section thereof to that of the cylindrical parts of the previously reduced end portions.

9. The method of making a seamless heat exchanger tube consisting inswaging; portions at both ends of an oversized tubular body to-a cylindrical part having a transverse section appreciably greater than that of the finished tube, then successively drawing the reduced cylindrical parts at the ends of the oversized tubular body through a die to have a transverse section" of the finished tube, and then forming an integral fin in the oversized tubular body and simultaneously reducing the transverse section thereof to that of the previously formed cylindrical end parts thereof.

10. The method of making a seamless heat exchanger tube consisting in swaging portions at both ends of an oversized tubular body to provide at both ends thereof a cylindrical part having a transverse section appreciably greater than that of the finished tube and a conical part at the extremity thereof, then successively drawing the said cylindrical end parts through a die to a transverse section corresponding to that of the finished tube, and then forming an in- 1 tegral fin in the oversized tubular body and simultaneously reducing its transverse section to that of the previously formed cylindrical parts at the ends thereof.

11. The method of making a seamless heat exchanger tube consisting in swaging a pormultaneously reduce the transverse section thereof to that of the previously reduced cylindrical parts at the ends thereof.

- 12. The method of making a seamless heat exchanger tube consisting in swaging a'portion at both ends of an oversized tubular body to provide at each end thereof a cylindrical part of appreciably greater transverse section than that of the finished tube and a conical part at the extremity thereof, then successively drawing'the said reduced cylindrical parts of the end portions of the oversized tubular body through a die to reduce each of the same to the transverse section of that of the finished tube, then drawing the said oversized tubular body through a die to form an integral fin thereon and simultaneously reducing the transverse section thereof to that of the previously reduced cylindrical parts at the ends thereof, and then cutting off theconical parts at the extremities of the cylindrical ends of the tu e.

13. The method of making-a seamless heat exchanger tube consisting in successively swaging the end portions of an oversized tubular body to provide in the said end portions cylindrical parts of appreciably greater transverse section than that of the finished tube and a conical part at the extremity of both thereof, then successively drawing the said cylindrical parts throiigh a die to re-- duce the same to the transverse section of the finished tube, and then forming a spirally disposed fin in the oversized tubular body and simultaneously reducing the transverse section thereof to that of the previously re duced end portions.

14. The method of making a seamless heat exchanger tube consisting in successively si /aging the end portions of an oversized tubular body to produce in each end thereof a cylindrical part of transverse section appreciably greater than that of the finished tube and a conical part the end thereof, then successively drawing the said cylindrical parts at the ends of the tubular body through a die to the same transverse section as that of the finished tube then drawing the said oversized tubular body through a die and simultaneously turning the die to form an integral spirally disposed tin and at the same time reduce the transverse section out the tubular body to that of the previously reduced cylindrical parts at the ends thereof, and finally cutting off the conical parts at the ends of the tube.

15. The method of making a seamless heat exchanger tube consisting in reducing an end portion of an oversized tubular body to a cylindrical part having the transverse section of the finished tube, and then forming a spirally disposed. fin in the said oversized tubular body and simultaneously reducin the transverse section thereof to that or the previously reduced cylindrical end part thereof.

16. The method of making a seamless heat exchan er tube consisting in swaging an end portion of an oversized tubular body to a cylindrical part having a. transverse section appreciably greater than that of the finished tube then drawing the reduced cylindrical end part through die to a transverse section corresponding to that of the finished tube, and then drawing the said oversized tubular body through a die and simultaneously turning the die to term a spirally disposed fin in the said oversized tubular body and at the same time reduce the transverse section thereof to that of the previously wreduced cylindrical end part thereof.

17. The method of making a seamless heat exchanger tube consisting in reducing a part of an oversized tubular body to the desired transverse section of the finished tube and then forming an integral fin in another part of the oversized tubular body and in so doing reducing its transverse section to that of the previously reduced part thereof.

. Signed by me this 19 day 031. FebJlQQQ.

' WM. L'ONSDALE. 

